Attempt To Free Heap Memory

int sqlite3_release_memory(int);

The sqlite3_release_memory() interface attempts to free N bytes
of heap memory by deallocating non-essential memory allocations
held by the database library. Memory used to cache database
pages to improve performance is an example of non-essential memory.
sqlite3_release_memory() returns the number of bytes actually freed,
which might be more or less than the amount requested.
The sqlite3_release_memory() routine is a no-op returning zero
if SQLite is not compiled with SQLITE_ENABLE_MEMORY_MANAGEMENT.